Acetic acid



Patented May 7,1935

E. ,Huscher, Midland DowChemmalfCom'pa was l g e'l No Masai-mama; bfib slices,

, Serial No..'701',182

" 8 claims; (Crist -116): j

- This invention concerns. a method of makin alkali metal acetate or acetic a'cidfrom propy lene. It is known 3' aqueous alkali .metal hydroxidejunder' pressure at high temperatures to produce alkali-"metal acetate. "1;? :Bgn From this. fact it wouldbe expected-that. the reaction of propylene under. similar 'conditions would lead to theiprodu'ction :ofalkalfmetal propionate. :We have found,;:however," thatqby reacting propylene 'lwith aqueous I-alkali :metal hydroxide, alkali metal acetate 1 is produced the principal product,"'very' littlewif anyQp'ropionate beinglformed: Such'reactionof propyclaims, itheifollowiriga description and example i a setting forthin detail only certain of the various ways in which the principle of our invention may be employed.

An autoclave is partially filled with an aqueous alkali metal hydroxide solution having a concentration of less than 40 per cent, preferably from 3 to 20 per cent. A basic aluminum compound, e. g. aluminum oxide, aluminum hydroxide, sodium aluminate, etc., is preferably, though not necessarily, dissolved in or intermixed with the alkaline solution as a reaction catalyst; The

basic aluminum compound may be added as such to the alkaline solution or formed therei'n'by adding an aluminum salt, e. g. aluminum chloride, aluminum nitrate, aluminum carbonate, etc. The basic aluminum compound'may be employed in any desired proportion, but usually about 0.3 of the chemical equivalent'of the alkali metal hydroxide used is suflicient. v Propylene or a hydrocarbon mixturecontain- 'ing propylene is then charged into the autoclave, preferably until the latter contains propylene in approximately equimolecularamount to the alkali metal hydroxide present, although any desired proportion of propylene may be employed. After the propylene has been charged into the mom? rm,

that eth len an :be rated an,

iwa i va therein is heatedwith stirring to a temperature betweeriiv30oixanda-;420;'.C., preferably". between 350 and 390 0., usually for from 1 to 10 hours.-

- ::The autoclave fis then cooled, .gas'iis'freleased therefrom, 'andf the; liquid reaction mixture is removed; :The liquid reaction mixture islconcen trated by evaporation, during which operation certainlorganicgbyproducts, erg. 'isopropyl alf 1 coholzand'jp lymers' of propylene, are. vaporized fromithe mixture and recovered in the condensed mixture may be. concentrated sufliciently to crystallize .a portion "of the alkali metal acetate product, the crystallinesproduct beingseparated from 10 vapors, leaving an. alkaline solution of. relatively purealkali-zmetal acetater 'If'des'ired, the liquid v its, alkaline-:mother liquor, and-"the latter reemployed; for the-oxidation of additional quantitiesvof .propylenem when operating. on a small scale, however, wenfind; it most' convenient to acidify the, concentrated liquor'with mineral acid,

'eL 'g. ...-sulphuric.;. orilhydrochloric acidiand. -to separate acetic acid. fronrthe acidified liquor by distillation.;i,, 1+

1; :Theriollowing :example illustrats one way 1 which the principle of our invention'has been the-, 'invention "19.3 grams of a 24.1 per cent aqueous hydroxide solution (containing I 0.342 mole of KOH) and 2 grams of aluminum oxide were applied, :but not :tolbe construedwasf limiting placed in anv iron bomb, and 18.1 grams (0.431

mole) of pr pylene was then charged into thev bomb, which was then sealed. The reaction mix- .and found to-contain approximately l gram of isopropyl alcohol and 3.5 grams of liquidpolymers I of propylene. The concentrated acetate solution remaining after the above mentioned distillation was acidified with sulphuric acid and aqueous acetic acid was distilled from the acidified liquor. There'was obtained 0.105 mole of acetic .acid, the yield thereofjbeing 30.6 per cent of theoretical,

based 'on-the 'quantity of potassium hydroxide autoclave, the latter sealed and the charge] r after. separating an acetate propylene under pressure with aqueous sodium' hydroxide and with'aqueouspotassiwn hydroxide in the absence of such catalyst;

Instead of employing pure propylene'in our process, a mixture of propylene with other--- gaseous or liquid hydrocarbons may be'ernployed For instance, when oil gas containing); mixture of ethylene, propyleneyand higherole'nnes ;is

reacted with aqueous alkali m'e tal hydrbxidf under the conditions hereinbefore described, ethylene and propylene arebofli into alkali metal acetate, whereas the higher either remain substantially unreacted or. are polymerized. The alkali metal acetate or acetic" acid product can readily be separated from the reacted. mixture by procedure. hereinbefnre described. a e a we I v expression acetate aproducti', "where employed vin the claims, refers to a product selected from theclass consistingof acetic acid and thereof. 7 g

Other modes of. applying the of our invention may be employed instead of those explained, change beinglmade asregards'the method herein disclosed, providedethe stepeor. steps stated by any of the followingeclaims nr thefequivalent of such stated step or steps be employed.

We therefore particularly point out and distinctly "claim :as our inventionz-l- 1. The method which comprises reacting propylene with an aqueous alkali :metal hydroxide solution, and thereafter separating acetate product from the reacted mixture.

2. The method which propylene with an aqueous alkali metal hydroxide solution under-pressure to a temperature between about300 C. and about 420 C., and flaereproduct mm the reacted mixture. I

3.J;In a met-hod of acetate, the step which consistsli inilheating propylene with an aqueous alkali metal hydroxide amiss emu solution in the presence of an inorganic basic aluminum'compound under pressure to a temperature between about 300 C. and about 420 C.

4. In a method of making an alkali metal acetate, the step which consists in heating propylene with an aqueous alkali metal hydroxide solution .of less than 40 percent concentration in the presence of an inorganic basic aluminum compound under pressure to a temperature between about 350 C. and about 390 C.

j 5. In a method of making an alkali metal acetate, the steps which consist in heating prowlene'wi-th-an'aqueous alkali metal hydroxide solution of not more than 20 per cent concentratipn im the presence of an inorganic basic aluminum compound under pressure to a temperature betwemabout 350 C. and about 390 C., concentrating thereacted liquor suificiently to crystallize alkali metal acetate therefrom, and

separating the crystalline product.

3 I Bela amethodrof acetic acid, the steps which consist in heating propylene with an aqueous alkali metal hydroxide solution of less than 20 per cent concentration in the presence of an inorganic aluminum compound under pressure to a temperature between about 350 C. and about 390 C., acidifying the reacted liquor with acid, and distilling acetic acid from the acidified liquor.

' 7.;Themethod whichcomprises heating a hydrocarbonmixtume containing propylene with an aqueous alkali metal hydroxide solution under pressure to a temperature between about 300 C. and about 420 0., and thereafter separating an acetate product from the reacted mixture.

8. In a method of making an alkali metal acetate, the step which consists in heating a gaseous hydrocarbon mixture containing ethylene and propylene with. an aqueous alkali metal hydroxi'de :selution inthe presence of an inorganic basic aluminium compound under pressure to a temperature between about 350 C. and about 390? (3., whereby ethylene 'and'propylene .both react to form alkali metal acetate. I

' EDGAR C. BRITTON;

HOWARD S. NU TIING.

MYRON E. 

